The MgAl2O4 ceramics were prepared by the conventional
solid-state ceramic route and the dielectric properties
studied in the microwave frequency region (3–13 GHz).
The phase purity and crystal structure were identified using
the X-ray diffraction technique. The MgAl2O4 spinel ceramics
show interesting microwave dielectric properties (εr = 8.75,
Qux f = 68 900 GHz (loss tangent = 0.00017 at 12.3 GHz),
τf =−75 ppm/◦C). The MgAl2O4 has high negative τf, which
precludes its immediate use in practical applications. Hence
the microwave dielectric properties of MgAl2O4 spinels were
tailored by adding different mole fractions of TiO2. The
εr and Q factor of the mixed phases were increased with
the molar addition of TiO2 into the spinel to form mixtures
based on (1−x)MgAl2O4-xTiO2 (x = 0.0−1.0). For x = 0.25 in (1−x)MgAl2O4-xTiO2, the microwave quality factor
reaches a maximum value of Qux f = 105 400 GHz (loss tangent
= 0.00007 at 7.5 GHz) where εr and τf are 11.035 and
−12 ppm/◦C, respectively. The microwave dielectric properties
of the newly developed 0.75MgAl2O4-0.25TiO2 dielectric is
superior to several commercially available low loss dielectric
substrates.

Dimethylacetals of ketones; cyclohexanone, acetophenone,
and benzophenone have been prepared by reacting
ketones with methanol under mild reaction conditions.
Large pore zeolites (H-Y and its rare earth metal, Ce3+, La3+,
and RE3+ modified forms), and mesoporous clay (K-10
montmorillonite and its cerium exchanged counterpart) with
regular pore structure, silica and silica-alumina have been
used as catalysts. Clay catalysts are found to be much more
active than zeolites, thanks to slightly bigger pore size. The
nature of the pores of the solid acid catalysts determine acetalization
efficiency of a particular catalyst. As evidenced
by the reaction time studies, the catalyst decay is greater
over the zeolites than over the clays. Carrying out the reaction
with ketones of different molecular sizes it is shown
that K-10 clays and rare earth exchanged H-Y zeolites are
promising environmentally friendly catalysts for their use in
the production fine chemicals.

Three enzymes, α-amylase, glucoamylase and invertase, were immobilized on acid activated montmorillonite K 10 via two independent techniques, adsorption and covalent binding. The immobilized enzymes were characterized by XRD, N2 adsorption measurements and 27Al MAS-NMR spectroscopy. The XRD patterns showed that all enzymes were intercalated into the clay inter-layer space. The entire protein backbone was situated at the periphery of the clay matrix. Intercalation occurred through the side chains of the amino acid residues. A decrease in surface area and pore volume upon immobilization supported this observation. The extent of intercalation was greater for the covalently bound systems. NMR data showed that tetrahedral Al species were involved during enzyme adsorption whereas octahedral Al was involved during covalent binding. The immobilized enzymes demonstrated enhanced storage stability. While the free enzymes lost all activity within a period of 10 days, the immobilized forms retained appreciable activity even after 30 days of storage. Reusability also improved upon immobilization. Here again, covalently bound enzymes exhibited better characteristics than their adsorbed counterparts. The immobilized enzymes could be successfully used continuously in the packed bed reactor for about 96 hours without much loss in activity. Immobilized glucoamylase demonstrated the best results.

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The surface acidity and basicity of mixed oxides of Zr and Y
and their mixed oxides have been determined by titration method
using Hammett indicators. The acid base properties are evaluated
on a common scale of acid strength. Liquid phase reduction of
cyclohexanone has been selected as a model reaction to correlate
catalytic activity.

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The electron donor properties of Pr6O11 activated at 300. 500 and 800°C are reported from the studies
on adsorption of electron acceptors of various electron affinity (7. 7, 8, 8-tetracyanoquinodimethane.
2, 3. 5, 6-tetrachloro-l, 4-benzoquin one. p-dinitrobenzene. and
m-dinitrobenzene) in three solvents (acetonitrile, 1,4-dioxan and ethyl acetate). The extent of electron
transfer during adsorption is understood from magnetic measurements and ESR spectral data. The corresponding
data on mixed oxides of Pr and Al are reported for various compositions, The acid / base
properties of these oxides are determined using a set of Hammett indicators.

The surface acidity and basicity of binary oxides of Zr with Ce and La are determined using a series of Hammet indicators and Ho,,max values are reported. The generation of new acid sites habe been ascribed to the charge imbalance of M1-O-M2 bonds, where M1 and M2 are metal atoms. Both Bronsted and Lewis acid sites contribute to the acidity of the oxides

The electron donor properties of Nd2O3 activated at 300, 500 and 800°C were investigated
through studies on the adsorption of electron acceptors of various electron affinities - 7, 7, 8,8-tetracyanoquinodimethane (2.84 eV). 2, 3, 5, 6-tetrachloro-l , 4-benzoquinone (2.40 eV).
p-dinitrobenzene (1.77 eV), and m-dinitrobenzene (1.26 eV) in solvents acetonitrile and
1, 4-dioxan. The extent of electron transfer during adsorption has been found from magnetic
measurements and electronic spectral data. The corresponding data on mixed oxides of
neodymium and aluminium are reported for various. compositions. The acid-base properties of
catalysts were also determined using a set of Hammett indicators.

The pillared montmorillonite has been prepared by exchanging
Na+ in the interlayer of montmorillonite with Al hydroxy cation followed
by calcination. Pillared clays are also prepared after exchanging
Na' ions with Ce, La, Sm-ions and then pillarcd with aluminium
oxides, The surface characterisation of the prepared catalysts has been
done using XRD and surface area measurements. To probe the acidic
property of the system, temperature programmed desorption (TPD)
of NH, has been done. Toluene alkylation by benzyl chloride has
been carried out for the evaluation of catalytic activity. The most
active system is found to be mixed Al/Zr pillarcd montrnorillonite.

The acidity of the various rare-earth exchanged zeolite-Y
catalysts has been examined by titration method using Hammett
indicators and is correlated with the catalytic activity of the
samples in the benzylation of 0-xylene.

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Surface acidity/Basicity of mixed oxides of La and Zn activated at three different temperatures were determined. The data have been correlated with the catalytic activity for liquid phase reduction of cyclohexanone in isopropanol.

The surface acidity/ basicity of TiO2 (rutile) and its sulphate modified
form have been determined by titration method using Hammett
indicators after activation at different temperatures. The electron
donating properties of these oxides are also studied from the adsorption
of electron acceptors of different electron affinity values. The
data have been correlated with the catalytic activity of these oxides
towards esterification of acetic acid using n-butanol, reduction of
cyclohexanone in isopropanol and oxidation of cyclohexanol in benzophenone.
Catalytic activity for esterification and oxidation reaction
parallels the acidity while that for reduction reaction parallels
the basicity of these oxides.

The changes in surface acidity/basicity and catalytic activity of cerium oxide due to surface modification by sulphate ion have been
investigated. Electron donor properties of both the modified and unmodified oxides have been studied using electron acceptors of
various electron affinity values, viz. 7,7,8,8-tetracyanoquinodimethane, 2,3,5,6-tetrachloro--l, 4-benzoquinone. p-dinitrobenzene and
m-dinitrobenzene in order to find out whether the increase in acidity on suphation is due to the generation of new acidic sites or they are
formed at the expense of some of the basic sites. The surface acidity/basicity has been determined using a set of Hammett indicators.
The data have been correlated with the catalytic activity of the oxides for esterification of acetic acid using l-butanol, reduction of
cyclohexanone with 2- propanol and oxidation of cyclohexanol using benzophenone.

The surface electron donor properties of sulphate modified stannic oxide have been determined from the
adsorption of electron acceptors of various electron affinities on the oxide surface. The acid base properties of
stannic oxide have been determined by titration method using Hammett indicators. Catalytic activities of the
oxide for esterification of acetic acid using n-butanol.reduction of cyclohexanone in 2-propanol and oxidation of
cyclohexanol with benzophenone have been studied. The data have been correlated with the surface electron
donor properties of these oxides. The activity for reduction and oxidation decreases and that for esterification
reaction increases on modification with sulphate ion. It has heen found that electron donating capacity decreased
when stannic oxide was modified with sulphate ion.

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The effect of diphenylmethane diisocyanate
(MDI) -polyethyleneglycol (PEG) resin on the cure characteristics and mechanical
properties of nitrile rubber/whole tyre eclaim-short nylon fiber
composite-was studied. At a constant loading of 5 phr, the resin composition
was varied. The minimum torque .,id (maximum - minimum) torque increased
with isocyanate concentration. Scorch time and cure time showed a reduction on
introduction of bonding agent. Properties like tensile strength, tear strength, and
abrasion resistance increased with increase in MDI/PEG ratio, and these
properties are higher in the longitudinal direction of fiber orientation.
Compression set increased with isocyanate concentration and the resilience
remain unchanged.

An asymmetric coplanar strip (ACS) fed dual band F-shaped antenna covering the 2.4/5.2 GHz WLAN bands is presented. The optimized dimensions of the proposed uniplanar antenna are 21 mm × 19 mm when printed on a substrate of dielectric constant 4.4 and height 1.6 mm. The dual band nature of the antenna is brought about by the various current paths in the F-shaped structure and the ground plane. The antenna exhibits nearly omnidirectional radiation characteristics and moderate gain in both the operating bands. Details of the antenna design, simulation, and experimental results are presented and discussed.

A packed bed bioreactor (PBBR) was developed
for rapid establishment of nitrification in brackish
water hatchery systems in the tropics. The reactors were
activated by immobilizing ammonia-oxidizing (AMONPCU-
1) and nitrite-oxidizing (NIONPCU-1) bacterial
consortia on polystyrene and low-density polyethylene
beads, respectively. Fluorescence in situ hybridization
demonstrated the presence of autotrophic nitrifiers belong
to Nitrosococcus mobilis, lineage of b ammonia oxidizers
and nitrite oxidizer Nitrobacter sp. in the consortia. The
activated reactors upon integration to the hatchery system
resulted in significant ammonia removal (P\0.01) culminating
to its undetectable levels. Consequently, a
significantly higher percent survival of larvae was observed
in the larval production systems. With spent water the
reactors could establish nitrification with high percentage
removal of ammonia (78%), nitrite (79%) and BOD (56%)
within 7 days of initiation of the process. PBBR is configured
in such a way to minimize the energy requirements
for continuous operation by limiting the energy inputs to a
single stage pumping of water and aeration to the aeration
cells. The PBBR shall enable hatchery systems to operate
under closed recirculating mode and pave the way for
better water management in the aquaculture industry.

Progesterone-receptor complex from freshly prepared hen oviduct cytosol acquired the ability to bind to
isolated nuclei, DNA-cellulose and ATP-Sepharose when incubated with 5-10 mM ATP at 4°C. The extent of
this ATP-dependent activation was higher when compared with heat-activation achieved by warming the progesterone-
receptor complex at 23 °C. The transformation of progesterone-receptor complex which occurred in a
time-dependent manner was only partially dependent on hormone presence. The ATP effect was selective in
causing this transformation whereas ADP, AMP and cAMP failed to show any such effect. The non-hydrolizable
analogs of ATP, adenosine 5'-[a,/3-methylene]triphosphate and adenosine 5-[/l,y-imido]triphosphate were also
found to be ineffective. Presence of 10 mM sodium molybdate blocked both the ATP and the heat-activation of
progesterone-receptor complex. Mn" or Mg` had no detectable effect on the receptor activation but the presence
of Ca" increased the extent of ATP-activation slightly. EDTA presence (> 5 mM) decreased the extent of
receptor activation by about 40 % and was, therefore, not included in the buffers used for activation studies.
Divalent cations were also ineffective when tested in the presence of 1- 5 mM EDTA. The
properties of progesterone-receptor complex remained intact under the above conditions when analyzed for
steroid-binding specificity and Scatchard analysis. However, the ATP-activated progesterone-receptor complex
lost the ability to aggregate when tested on low-salt sucrose gradients. ATP was equally effective in activating
the rat-uterine estradiol-receptor complex at 4 "C and influenced the transformation of 4-S receptor form into
a 5-S form when analyzed on sucrose gradients containing 0.3 M KCI. The presence of ATP also increased the
rate of activation of progesterone-receptor complex at 23 °C. These findings suggest a role for ATP in receptor
function and offer a convenient method of studying the process of receptor activation at low temperature and
mild assay conditions.

Active microwave imaging is explored as an imaging
modality for early detection of breast cancer. When exposed to
microwaves, breast tumor exhibits electrical properties that are
significantly different from that of healthy breast tissues. The
two approaches of active microwave imaging — confocal microwave
technique with measured reflected signals and microwave tomographic
imaging with measured scattered signals are addressed here. Normal
and malignant breast tissue samples of same person are subjected to
study within 30 minutes of mastectomy. Corn syrup is used as coupling
medium, as its dielectric parameters show good match with that of
the normal breast tissue samples. As bandwidth of the transmitter is
an important aspect in the time domain confocal microwave imaging
approach, wideband bowtie antenna having 2:1 VSWR bandwidth
of 46% is designed for the transmission and reception of microwave
signals. Same antenna is used for microwave tomographic imaging too
at the frequency of 3000 MHz. Experimentally obtained time domain
results are substantiated by finite difference time domain (FDTD)
analysis. 2-D tomographic images are reconstructed with the collected
scattered data using distorted Born iterative method. Variations of
dielectric permittivity in breast samples are distinguishable from the
obtained permittivity profiles.

Influence of acute salinity stress on the immunological and physiological response of Penaeus monodon to white spot
syndrome virus (WSSV) infection was analysed. P. monodon maintained at 15‰ were subjected to acute salinity changes to 0‰
and 35‰ in 7 h and then challenged orally with WSSV. Immune variables viz., total haemocyte count, phenol oxidase activity
(PO), nitroblue tetrazolium salt (NBT) reduction, alkaline phosphatase activity (ALP), acid phosphatase activity (ACP) and
metabolic variables viz., total protein, total carbohydrates, total free amino acids (TFAA), total lipids, glucose and cholesterol were
determined soon after salinity change and on post challenge days 2 (PCD2) and 5 (PCD5). Acute salinity change induced an
increase in metabolic variables in shrimps at 35‰ except TFAA. Immune variables reduced significantly (Pb0.05) in shrimps
subjected to salinity stress with the exception of ALP and PO at 35‰ and the reduction was found to be more at 0‰. Better
performance of metabolic and immune variables in general could be observed in shrimps maintained at 15‰ that showed
significantly higher post challenge survival following infection compared to those under salinity stress. Stress was found to be
higher in shrimps subjected to salinity change to lower level (0‰) than to higher level (35‰) as being evidenced by the better
immune response and survival at 35‰. THC (Pb0.001), ALP (Pb0.01) and PO (Pb0.05) that together explained a greater
percentage of variability in survival rate, could be proposed as the most potential health indicators in shrimp haemolymph. It can be
concluded from the study that acute salinity stress induces alterations in the haemolymph metabolic and immune variables of
P. monodon affecting the immunocompetence and increasing susceptibility to WSSV, particularly at low salinity stress conditions